Well, seeing the Riders who are in this picture (and the previous one), I'm fairly sure it's a reference of "Rider Prison" from the Masked Rider Live & Show 10th Anniversary.
It used to have a small clip on Youtube but seems like they removed it so you can take a look on Niconico video only.
BTW, the original actors for all 5 Riders who bullied Kuuga, reprised their role during this Live.